Measurements of Dissolved Organic Carbon (DOC) in sea water by high temperature combustion method Academic Article uri icon

abstract

  • Dissolved organic carbon (DOC) is the largest organic carbon reservoir in sea water and plays an important role in the marine carbon cycle and other biogeochemical processes in the ocean. Accurate and precise determination of the DOC concentration in sea water is thus a prerequisite for any interpretation of DOC biogeochemistry. A key factor in analytical quality control is an accurate determination of the blank. The assessment and distinction of DOC blanks are essential for the precise measurements of oceanic DOC. The total DOC blank includes instrument and water blanks in the high temperature catalytic oxidation (HTCO) method. DOC can be measured accurately using the HTCO method only when the instrument blank is correctly distinguished from the total DOC blank and corrected in the sample measurements. Low DOC blanks can be achieved by extensive conditioning of new catalysts and the whole instrument system, whereas instrument blanks can be quantified by subtracting the water blank from the total DOC blank. We have been able to produce low carbon nanopure water [2mol/dm3(C)] and have a low instrumental blank [<5-6 mol/dm3(C)] when using the HTCO method. Results of concentrations and distributions of DOC in the Gulf of Mexico and the North Atlantic are oceanographically consistent. Results from DOC measurements on samples from the international DOC methods comparison program further confirmed our low values of both nanopure water and the instrument blank.

published proceedings

  • Acta Oceanologica Sinica

author list (cited authors)

  • Laodong, G., & Santschi, P. H.

complete list of authors

  • Laodong, G||Santschi, PH

publication date

  • December 1997